﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


class trapezoidArea
{
    static void Main(string[] args)
    {
        Console.WriteLine("Enter b1 side");
        double b1 = Convert.ToDouble(Console.ReadLine());
        Console.WriteLine("Enter b2 side");
        double b2 = Convert.ToDouble(Console.ReadLine());
        Console.WriteLine("Enter H");
        int h = Convert.ToInt32(Console.ReadLine());
        double area = (((b1 + b2) / 2) * h);
        Console.WriteLine("Area is: {0}", area);
    }
}

